Seasonal change in the utilization of tree cavities by wildlife in Obihiro City

Abstract

To determine how forest wildlife use tree cavities, we investigated seasonal changes in species which used tree cavities and the numbers of tree hollows used in the daytime and nighttime over a year in Obihiro City, Hokkaido, Japan. We found 3 species of woodpeckers, which are primary producers of tree cavities, and 12 species of other birds and mammals, which are secondary users of the cavities. The tree cavities were used both daytime and nighttime throughout most of the year. The highest rates of use were recorded in June in daytime and July at nighttime. Although seasonal trends were apparent, the rates of use were almost the same between daytime and nighttime in each season. Although the rates of use by secondary user birds were higher in the summer breeding season, the great spotted woodpecker, lesser spotted woodpecker, Eurasian nuthatch, and Russian flying squirrel used cavities throughout the year. Other species were also observed using the cavities for roosting or resting. Thus, different wildlife use tree cavities in various ways.